TESTICULAR CANCER STAGING

Testicular cancer: serum markers
Germ cell tumours may express and secrete into the bloodstream relatively specific and readily measurable proteins. These tumour markers (with the exception of PLAP) are useful in diagnosis, staging, prognostication, and monitoring of response to treatment.

Onco-fetal proteins
Alpha-fetoprotein (AFP) is expressed by trophoblastic elements within 50 - 70% of teratomas and yolk sac tumours. With respect to seminoma, the presence of elevated serum AFP strongly suggests a non-seminomatous element. Serum half-life is 3 - 5 days; normal <10ng/ml.

Human chorionic gonadotrophin (hCG) is expressed syncytiotrophoblastic elements of choriocarcinomas (100%), teratomas (40%), and seminomas (10%). Serum half-life is 24 - 36h. Assays measure the ?-subunit; normal <5mIU/ml.
When used together, 90% of patients with advanced disease have elevation of one or both markers; less among patients with low-stage tumours.

Cellular enzymes
Lactate dehydrogenase (LDH) is a ubiquitous enzyme, elevated in serum for various causes, therefore less specific. It is elevated in 10 - 20% of seminomas, correlating with tumour burden, and is most useful in monitoring treatment response in advanced seminoma.

Placental alkaline phosphatase (PLAP) is a fetal isoenzyme, elevated in up to 40% of patients with advanced germ cell tumours. It is not widely used as it is non-specific. May be elevated in smokers.

Clinical use
These markers are measured at presentation, 1 - 2 weeks after radical orchidectomy, and during follow-up to assess response to treatment and residual disease.
Normal markers prior to orchidectomy do not exclude metastatic disease; normalization of markers post orchidectomy cannot be equated with absence of disease; and persistent elevations of markers post- orchidectomy may occur with liver dysfunction and hypogonadotrophism, but usually indicate metastatic disease.

Staging
- Sx Markers not available 
- S0 Markers normal 
- S1 LDH 1 - 1.5 Ã normal upper limit; hCG <5000 mIU/ml; and AFP <1000ng/ml 
- S2 LDH 1.5 - 10 Ã normal; hCG 5000 - 50,000; and AFP 1000 - 10,000 
- S3 LDH >10 Ã normal; hCG >50,000; and AFP >10,000

Testicular cancer: pathology and staging
90% of testicular tumours are malignant germ cell tumours (GCT), split into seminomatous and non-seminomatous (NS) GCTs for clinical purposes. Seminoma, the most common germ cell tumour, appears pale and homogeneous. NSGCTs are heterogeneous and sometimes contain bizarre tissues such as cartilage or hair. Metastases to the testis are rare, notably from the prostate (35%), lung (19%), colon (9%), and kidney (7%).

The right testis is affected slightly more commonly than the left; synchronous bilateral TC occurs in 2% of cases. TC spreads by local extension into the epididymis, spermatic cord, and, rarely, the scrotal wall. Lymphatic spread occurs via the testicular vessels, initially to the para-aortic nodes. Involvement of the epididymis, spermatic cord, or scrotum may lead to pelvic and inguinal node metastasis. Blood-borne metastasis to the lungs, liver, and bones is more likely once the disease has breached the tunica albuginea.

TC is staged using various classifications, most recently the TNM (2002) system . Herein, T stage is pathological, N stage involves imaging, and M stage involves physical examination, imaging, and biochemical investigations. An additional S category is appended for serum tumour markers.